This invention relates to a high performance metalworking fluid that has lubricating and extreme pressure/anti-wear properties and is environmentally safe, biodegradable, and non-hazardous, comprising a methyl ester of fatty acids or triglycerides component combined with a polar non-chlorine extreme pressure additive.
Soybean oil and vegetable oil triglycerides are heterogeneous products and may be converted to esters by a variety of processes, e.g. Demmering et al., U.S. Pat. No. 5,773,636 and Stidham et al., U.S. Pat. No. 6,127,560. Chlorinated methyl esters of soybean oils are known from Kusch, U.S. Pat. No. 6,028,038. A methyl soyate cleaning agent is described in Opre et al., U.S. Pat. No. 6,096,699. Oil lubricating additives are also known, e.g. O'Brien, J. A., Lubricating Oil Additives, Handbook of Lubrication, p. 301-315, Vol. II, Edited by E. Richard Booser, CRC Press, Inc., 1984; Gergel, W. C., Lubricant Additive Chemistry, The International Symposium Technical Organic Additives and Environment, Interlaken, Switzerland, May 24-25, 1984, The Lubrizol Corporation. Biodegradable triglyceride-based lubricants are described in e.g. Stewart et al., U.S. Pat. No. 4,948,521 and Naegely, U.S. Pat. No. 5,641,734. Soluble oil metalworking fluids based on soybean oil are described in Lightcap, U.S. Pat. No. 6,204,225. Also known are metalworking compositions with chlorine-free extreme pressure agents, e.g. U.S. Pat. No. 5,908,816.
Most traditional metalworking fluids are based on mineral oils that present potential environmental hazards. These formulations have been widely used for about thirty years. The most difficult metalworking applications (such as fine-blanking heavy gauge carbon steels, broaching, and drawing of stainless steel tubes and wires) require high performance metalworking fluids containing chlorinated paraffins. Recently however, the use of chlorinated paraffins has been questioned due to hazards to workers and the environment. The corrosiveness of chlorinated paraffins' decomposition products, primarily hydrogen chloride, is a concern. A more serious problem is presented at incineration facilities where incineration temperatures are not high enough, producing highly toxic and cancer-causing waste products. Previous attempts to use non-chlorinated replacements have failed in metalworking requiring high performance lubricating and extreme pressure/anti-wear properties.
There is a need for a high performance, economical, environmentally safe metalworking fluid. There is a growing need for effective, biodegradable soy-based straight oil and soluble oil metalworking fluids. For example, Section 9002 of the 2002 Farm Bill mandates federal procurement of biobased products. However, no existing preparations have been able to effectively replace chlorine-containing mineral oil-based metalworking fluids.